I propose that we start migrating towards making slicing of stack
data un- safe, first by making it a warning, enabled with -w. Then
making it an error.

I reported this quite some time ago, but unfortunately, it has yet to be
fixed.
https://issues.dlang.org/show_bug.cgi?id=8838
The bizarre thing though is that in the original thread where I brought it up,
some folks fought it, arguing that it should be considered safe. However,
slicing a static array is no different from taking the address of a local
variable, so they should definitely be treated the same.
On a related note, I very much wish that there was no implicit slicing of
static arrays in the language. It's just begging for bugs IMHO - precisely for
the same kinds of reasons that automatically converting a local variable to a
pointer to that variable would create bugs. But unfortunately, I think that
fix that now would be a very tough sell.
- Jonathan M Davis